The present invention relates to tennis balls having electrically conductive outer surfaces for use in a computer system for assisting an umpire in a tennis match.
In a tennis match a tennis ball may travel at 100 m.p.h. An umpire or linesman who may be 30 feet from a contact of that ball with the surface of the tennis court is throughout the match required to decide whether the ball bounced in-play or out-of-play.
Such a decision involves comparing the position of an area of contact with the positions of certain lines on the court. These lines may be marked on or attached to the court in various ways or may indeed be an integral part of the court surface itself. Such lines include the line of the top of the net dividing the court into two halves.
As an indication of the degree of difficulty of such a decision, if the closest point of an area of contact to a specific line is 1 inch from that line and if the ball was travelling at 100 m.p.h. immediately prior to contact and if the umpire or linesman concerned is 30 feet from the contact, it can be very difficult for him to judge whether the ball did or did not touch the line. Judgements of similar or greater difficulty can frequently be required from an umpire or linesman during a tennis match. Furthermore his decision is required as soon as possible after the bounce and preferably before the ball has been struck again after the bounce. At 100 m.p.h. a ball will travel the full length of a tennis court in about 1/2 second.
If in the example above, the closest point of the area of contact to the line had been 6 inches instead of 1 inch the judgement would generally be easier. This suggested distance of 6 inches is purely arbitrary, automatic decisions could be provided by extensions of the system to be described for a ball which bounced or landed anywhere on the court. In general, however, the umpire or linesman requires assistance in cases where the ball bounces closer to a line than a few inches. It is an object of this invention to provide an umpire, automatically with an accurate and timely decision for such cases.
Quite different situations arise in a tennis match where it is much simpler for an umpire to decide unaided whether the ball is in-play or out-of-play and hence to decide the latest score than to use an automatic system to make these decisions. For example, when a player strikes a ball before it bounces it is considered according to the rules of tennis that had the ball bounced it would have bounced in-play and therefore no decision of the type given in the example of the previous paragraphs is required. Again if a player hits a ball completely out of court, then although by expensive extensions of the system to be described it could operate similarly to the example, it will be much simpler and more convenient for an umpire to make the decisions mentioned above. Again if during a rally a player catches the ball and puts it in his pocket, it is much simpler for an umpire to make such decisions. cl SUMMARY OF THE INVENTION
The system has therefore been designed so that an umpire is provided with automatic decisions where difficult and rapid judgements are required as previously exemplified, but can himself input information to the computer system when this is simpler. An umpire's input unit may for example be a keyboard connected to his visual display unit (VDU) and enabling him to interact with the computer system by, say, requesting the computer to display on his VDU statistics accumulated during the match. In the system to be described the umpire is empowered to override the automatic system at all times except where simultaneous input of information occurs from both umpire and from a contact of the ball giving rise to an automatic decision as to whether the ball bounced or landed in-play or out-of-play.
With extensions of the system to be described an umpire could, by using his input unit, control output of information from the computer to a public scoreboard or a public address system. An umpire's input unit could alternatively be a voice input unit causing the computer to respond to his voice commands.
The basic computer system to be described in greater detail hereinafter has been designed with the object of assisting an umpire in a tennis match, particularly where difficult judgements are required to be rapidly made as to whether a ball has bounced or landed in-play or out-of-play. The design is such that the system can be expanded for example by the addition of a public scoreboard or public address system to which the computer can output information under the control of the umpire. Likewise there are several possible alternative input units the umpire could use such as a keyboard or a voice input unit and the basic system can be expanded to receive information input from for example impacts of the ball with the top of the tennis net and say from signals enabling detection of a foot-fault when a player serves.
According to an important aspect of the present invention there is provided a computer system for assisting an umpire in a tennis match, means comprising a plurality of tennis balls for playing in said tennis match, each of said tennis balls having a covering surface of cloth which is electrically conductive. The computer system also includes: means comprising a plurality of flat form, multi-conductor, flexible cables attached to playing surfaces of a tennis court for enabling in conjunction with said tennis balls the production of first output electrical signals, said first output electrical signals being indicative of the locations on said tennis court where the said balls bounce; means comprising a plurality of computer terminals for transmitting or receiving as directed by said umpire second electrical signals in connection with the occurrence of discrete events associated with said tennis match; indicator means comprising a plurality of indicator devices for indicating in response to applied control signals the status of one or more selected parameters in said tennis match; and means comprising said computer responsive to said first output electrical signals and said second electrical signals for providing in accordance with the rules of tennis control signals for application to said indicator means whereby the status of said selected parameters in said tennis match can be indicated.